Systematic studies of Elaphoglossum section Polytrichia (Dryopteridaceae)

Elaphoglossum is the largest genus of the largest family of ferns, the Dryopteridaceae. It has over 600 species distributed in the temperate and tropical regions of the world, but it is especially diverse in the Neotropics, where ca. 80% of the species occur. Morphologically, the genus is usually characterized by simple entire leaves, free veins, acrostichoid sori, and phyllopodia. One of the major clades within Elaphoglossum is the subulate-scaled clade, which includes all species with subulate scales on the leaves. These scales are often patent and enrolled lengthwise, imparting a bristly or shaggy appearance to the plants. Previous studies have suggested that the subulate-scaled clade is composed of two subclades distinguished by the presence versus absence of hydathodes. The non-hydathodous clade corresponds to Elaphoglossum section Polytrichia and is the main focus of this study. The dissertation comprises four chapters that were prepared for publication in different peer-reviewed journals. The first chapter is a molecular phylogeny of the subulate-scaled species of Elaphoglossum based on DNA sequence data from three plastid markers (atpβ-rbcL, rps4-trnS, and trnL-trnF). The results of this study provide the bases for the other three chapters, which include a nomenclatural synopsis of E. sect. Polytrichia, a monographic revision of the Apoda clade of E. sect. Polytrichia, and a floristic treatment of the Brazilian species of E. sect. Polytrichia. In Chapter 1, all well-established groups of Elaphoglossum were recovered with high statistical support, including a subulate-scaled clade composed of two (weakly supported) subclades distinguished by the presence vs. absence of hydathodes. Phylogenetic relationships within each of these subclades are discussed and several groups are suggested for future monographic study. In Chapter 2, I present a nomenclator for the 52 species of E. sect. Polytrichia (i.e., the non-hydathodous clade). All taxa are enumerated and accompanied by place and date of publication, information on types, synonymy, distributional notes, and pertinent remarks. A map of geographic distribution for the section is provided for the first time. One new species and several other nomenclatural changes are suggested. In Chapter 3, I provide a monographic treatment for the 13 species of the Apoda Clade of Elaphoglossum. Species of this clade are characterized by the presence of lustrous and brightly colored stem scales, small glandular hairs, and evenly distributed scales on petioles, costae, and laminar surfaces. One new species is suggested. To facilitate the identification of species, I provide illustrations, descriptions, comments, synonymy, distribution maps, and an identification key to all 13 species in this group. Chapter 4 follows the same format of the previous one, but includes only the species of E. sect. Polytrichia that occur in Brazil. Eleven species are recognized in this last chapter, including two newly described ones